JPS58108394A - Heat exchanger - Google Patents

Abstract

PURPOSE:To improve the performance of a heat exchanger comprising a plurality of heat transfer tubes of two kinds or more passing through a plurality of fins by a construction wherein heat conduction preventing portions are provided between the different kinds of heat transfer tubes of the fins. CONSTITUTION:In a condenser for use in an air conditioner, a refrigerant gas at a high temperature and a high pressure flows through a heat tube 2 of a large diameter and then through a heat tube 3 of a small diameter while heat exchange is conducted between it and air so that it is cooled and changed into liquid refrigerant. Between the two kinds of heat transfer tubes 2, 3 within the fin 1, plurality of elongated rectangular punched holes 6 serving as heat conduction preventing portions of the fins 1 are provided. These punched holes 6 extend in the longitudinal direction of the fins 1 and are disposed in a row or a plurality of rows at the same space interval as the pitches of the heat transfer tubes 2, 3. Thus, the length of shortest heat conduction route l' from the heat transfer tube 2 to the heat transfer tube 3 increases so as to prevent effectively the heat conduction inside the fins 1 thereby improving the performance of the heat exchanger.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger, and particularly to a heat exchanger suitable as a condenser for a heat pump type room air conditioner.

Conventionally, in order to improve the performance of air conditioners, the degree of supercooling of the liquid refrigerant flowing out from the heat exchanger that acts as a condenser was increased, and the amount of heat released was increased by an amount corresponding to the temperature drop. Measures are being taken to improve capacity. In this case, in the liquid single phase region, there are problems such as the high pressure increases due to the low heat transfer coefficient and the need to increase the amount of refrigerant charged.

For this reason, if the diameter of the heat exchanger tube in the part of the condenser where the liquid refrigerant is supercooled is made smaller than the diameter of the other heat exchanger tubes, 1. The above problems can be solved.

Incidentally, the heat transfer coefficient αML of the liquid refrigerant in the heat exchanger from the refrigerant to the tube surface is generally given by the following equation (1).

ζ Here, λL is the thermal conductivity %d1 is the tube inner diameter, RoL is the Reynolds number, Pl is the Prandtl number, and C is a constant. The Reynolds numbers B and L are the pipe inner diameter d, and the refrigerant circulation Jj flow rate Qr.
Therefore, when Expression (1) is expressed in terms of the relationship between heat transfer coefficient "IL" and tube inner diameter d1, it becomes the relationship of Expression (2).

aH,s*d,-',Lu,. 10110
0.11.0110. (2) Therefore, if the pipe inner diameter dIt-1 of the liquid refrigerant section in the heat exchanger (for example, the supercooling section 1 is reduced to half of the conventional one, the heat transfer coefficient "ML" will improve by approximately &5 times from equation (2). do.

Furthermore, since the pipe inner diameter of the liquid portion is made smaller by "dot", the increase in the amount of refrigerant sealed into the air conditioner can be suppressed to a smaller amount than in conventional devices.

In this way, by making the pipe diameter of the subcooling section smaller than the pipe diameter of the other parts in the condenser, the above-mentioned problems can be solved.

FIG. 1 shows a heat exchanger as a condenser in which the pipe diameter of the subcooling section is smaller than the pipe diameter of other parts.

The heat exchanger shown in this figure is constructed by passing a plurality of two types of heat transfer tubes 2 and 3 having different diameters through a plurality of fins 1 arranged in parallel with a distance between them.

In this heat exchanger, the high-temperature, high-pressure gas refrigerant discharged from the compressor flows from the inflow pipe of the condenser, and is shown by arrow 4.
The refrigerant becomes a high-temperature, high-pressure liquid refrigerant as it passes through the large-diameter heat transfer tube 2 while exchanging heat with air and gradually dissipating heat.

Thereafter, this high-temperature, high-pressure liquid refrigerant flows to a heat transfer tube 3 with a small diameter attached to the side of the air ventilator of the fin 1. As a result, the liquid refrigerant is further cooled and flows out of the condenser, passes through a pressure reducer and an evaporator (not shown), and is sucked into the compressor again as a low-temperature, low-pressure gas refrigerant.

As mentioned above, the heat exchanger as a condenser has fins 1,
A structure in which heat transfer tubes 2.3 having different pipe diameters are integrated has good handling and productivity, but there are some problems. Compared to the temperature of the refrigerant in the heat exchanger tube 2 with a large diameter, the temperature of the refrigerant in the heat exchanger tube 3 with a small diameter where the liquid is supercooled is considerably lower.

Although it varies depending on the operating conditions, the temperature difference between heat exchanger tubes 2 and 3 is 5~
It can also become 20C. In this case, since the heat exchanger tubes 2 and 3 are connected to the fins 1, heat transfer from the heat exchanger tubes 2 to 3 occurs due to heat conduction through the fins 1, resulting in an unfavorable state for the condenser. Therefore, it is necessary to prevent heat conduction within the fins 1 from the heat exchanger tubes 2 to 3.

An object of the present invention is to provide a heat exchanger that can effectively prevent heat conduction within the fins between two or more types of heat transfer tubes having different tube diameters or different fluid temperatures.

A feature of the present invention is that in a heat exchanger in which a plurality of heat transfer tubes of two or more types having different tube diameters or temperatures of fluids to be passed are passed through a plurality of fins arranged in parallel with a distance from each other, each fin is A heat conduction inhibiting portion is provided between the different types of heat transfer tubes, and with this configuration, the above object can be reliably achieved.

The present invention will be explained below based on the drawings.

FIG. 2 and FIG. 17 show various embodiments of the present invention, and show a portion surrounded by a dashed line in FIG. 1 and designated by the reference numeral 5.

FIG. 2 shows two types of heat exchanger tubes 2.
An embodiment is shown in which a plurality of punched holes 6 are formed between the fins 1 and 3 to serve as a portion for inhibiting heat conduction of the fins 1. These punched holes 6 are formed in an elongated rectangular shape in the length direction of the fin 1.
They are provided in a row in the sparse direction of the fins 1 at the same spacing as the arrangement pitch of the heat transfer tubes 2.3.

In this embodiment, when heat is conducted from the heat exchanger tube 2 to the heat exchanger tube 3 within the fin 1, or conversely from the heat exchanger tube 3 to the heat exchanger tube 2, the presence of the punched hole 6 allows the heat exchanger tube 2 to Since the length t' of the shortest heat conduction path through which heat is transferred from the heat exchanger tube 2 to the heat exchanger tube 3 becomes longer than the straight line distance t connecting .3, it is possible to effectively inhibit heat conduction within the fin l. can.

In this embodiment, the shape of the punched hole 6 is not limited to an elongated rectangular shape, but may be oval, oval, or other shapes.

Next, FIGS. 3 to 7 show modifications to the embodiment shown in FIG. 2, and FIG. 3 shows heat transfer tubes 2.3.
An example is shown in which two rows of punched holes are formed in a staggered manner in the length direction of the heat exchanger tube 2, and FIG. 9 and heat transfer tube 3
Fig. 5 shows an example in which two rows of circular arc-shaped perforations 10 are formed with the center of the radius as the center of the perforation. Figure 6 shows an example of forming 1.12 holes, and Figure 6 shows three rows of narrow punched holes '13.
, 14.15t, shows an example in which the punched holes 14 in the middle are arranged in a staggered manner in the length direction of the fin 1 with respect to the punched holes 13° 15 on the outside. An example is shown in which one long punched hole 16 is formed with a connecting portion left at the end. Also in the embodiments shown in FIGS. 3 to 7, by providing punched holes,
Heat conduction between the heat exchanger tubes 2 and 3 within the fin 1 can be inhibited.

Next, Fig. 8 shows an embodiment in which cuts are made between the heat transfer tubes 2°3 in the fin l as a heat conduction inhibiting part, and the first to fifth cuts 9 are made 16 to 20 tons. ing. And the first. 3rd degree 5th notch 16, 18
．． 20 are formed in the length direction of the fin 1 at the same intervals as the arrangement pitch of the heat exchanger tubes 2.3, and the second notches 17 are formed in the first . The third incisions 16 and 18 are formed in a staggered manner, and the fourth incision 19 is formed between the third incisions 16 and 18. Fifth cut 18°2
It is formed in a staggered manner between 0 and 0. In this embodiment, due to the presence of the first to fifth cuts 16 to 20, the length of the shortest heat conduction path from the heat exchanger tube 2 to the heat exchanger tube 3 with respect to the straight line distance t connecting the heat exchanger tubes 2.3. t' becomes very long,
Heat conduction between the heat transfer tubes 2.3 within the fins 1 can be significantly inhibited.

Furthermore, FIG. 9 shows a modification of the embodiment shown in FIG. 8, in which one cut 21 is made at the end of the fin 1 in the longitudinal direction, leaving a connecting part, In this embodiment as well, heat conduction can be inhibited as in the embodiment shown in FIG. 8 above.

Next, in Figures 10 and 11, two sets of cuts are made with a certain width between the heat transfer tubes 2.3 in the fin l, and a strip formed into a bridge shape is formed between the cuts. This shows an example in which two rows of strips 22 and 23 are formed between the heat exchanger tubes 2 and 3. The strips 22 and 23 are formed at the same interval as the arrangement pitch of the heat transfer tubes 2.3 in the length direction of the fin 1, and are arranged in a staggered manner. In this embodiment, the holes formed by cutting and raising the lltl pieces 22 and 23 obstruct heat conduction between the heat transfer tubes 2 and 3 within the fins 1, and the thin pieces Air flow 4 due to 22°23
can be disturbed and the strips 22,23 themselves can be used as effective heat transfer surfaces.

Further, FIGS. 12 and 13 show a modification of the embodiment shown in FIGS. 10 and 11, in which each of the strips 22 and 23 are cut at the middle in the longitudinal direction to form a notch 22'.

23' is formed so that the air flow 4t can be disturbed even more effectively.

Subsequently, FIGS. 14 and 15 show the next embodiment in which a thin wall portion 24 of a constant width is formed between the heat transfer tubes 2 and 3 in the fin 1 as a heat conduction inhibiting portion. In this embodiment, by forming the thin portion 24t, the cross-sectional area of the fin 1 for transmitting heat can be reduced, thereby inhibiting heat conduction.

16 and 17 show that on the front and back screens between the heat transfer tubes 2 and 3 in the fin 1, as a heat conduction inhibiting part,
A set of long grooves 25° 25' in the longitudinal direction of the fin 1 and a groove 26
．． An example in which a set of 26' is formed is shown. In this embodiment as well, by providing a set of grooves 25° 25' and a set of grooves 26, 26', a thin walled portion is formed, and the cross-sectional area of the fin lO heat transmitting portion is reduced, which impedes heat conduction. It is possible.

In addition, in this embodiment, the groove is the fin 16 surface.

The grooves are not limited to forming two sets on the back side, but may be formed with just one set, or three or more sets may be formed on the back side.The shape of the grooves is not limited to the V-shape shown in the figure, but may be U-shaped or mouth-shaped. good,
Further, the grooves are not limited to those that penetrate in the length direction of the fin 1, and a plurality of short grooves may be formed at intervals in the length direction of the fin 1.

As explained above, according to the present invention, the heat conduction inhibiting portion provided between two or more types of heat exchanger tubes having different pipe diameters or fluid temperatures inhibits heat conduction between different types of heat exchanger tubes within the fin. However, since heat transfer can be reduced, different types of heat exchanger tubes will not have a thermal influence on each other, and the performance as a heat exchanger can be improved.゛・Furthermore, when the present invention is used as a condenser, the diameter of the heat exchanger tube can be made smaller than the diameter of the heat exchanger tube in other parts in the liquid refrigerant single-phase region, so that the heat on the refrigerant side in the tube can be reduced. The transmission rate can be increased compared to conventional air conditioners, and the amount of refrigerant sealed can be reduced compared to conventional air conditioners.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a vine exchanger as a condenser consisting of two types of heat transfer tubes, and Fig. 2 is a front view of main parts of an embodiment of the present invention. 5, 6 and 7 are respectively front views showing modifications to the embodiment shown in FIG. 2, FIG. 1O is a front view of essential parts of another embodiment of the present invention, and FIG. 11 is a side view of one of the strips in Figure 10, the first
2 and 13 are front and side views showing modifications to the embodiment shown in FIGS. 10 and 11, and FIG.
15 is a cross-sectional enlarged cross-sectional view of FIG. 14, FIG. 16 is a front view of a main portion of still another embodiment of the present invention, and FIG. This can be seen in the enlarged cross-sectional view of FIG. 16. l...Fin, 2.3...Different types of heat exchanger tubes, 6-16
...Punched holes as heat conduction inhibiting parts, 17-21
...Open incision, 22.23...Same strip, 22'. 23'... Notch portion formed in the longitudinally intermediate portion of the strip, 24... Thin wall portion as a heat conduction inhibiting portion, 25.
25', 26.26'...open groove, t...straight line distance between different types of heat transfer tubes, t'...shortest heat conduction path. %r figure

Claims (1)

[Claims] 1. A plurality of fins arranged side by side with a distance maintained between them,
A heat exchanger that passes through two or more heat transfer tubes of two or more types with different diameters or fluid temperatures. 2. The heat exchanger according to claim #I1, characterized in that the heat conduction inhibiting portion is a punched hole formed long in the length direction of the fin. 3. The heat exchanger according to claim 1, wherein the heat conduction inhibiting portion is an elongated notch formed in the longitudinal direction of the fin. 4. The heat conduction inhibiting portion is long in the length direction of the fin.
2. The heat exchanger according to claim 1, wherein the heat exchanger is a strip formed by making a series of cuts and bending the space between the cuts into a bridge shape. 5. The heat exchanger according to claim 4, wherein the strip constituting the heat conduction inhibiting portion is cut at an intermediate portion in the length direction. 6. The heat exchanger according to claim 1, wherein the heat conduction inhibiting portion is a thin wall portion formed long in the length direction of the fins between different types of heat transfer tubes of each fin. .